Re: Ada-Oriented GUI

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On 2018-03-24 12:36, Alejandro R. Mosteo wrote:

> Rx Observer contract:
> 
> OnNext* (OnCompleted | OnError)?
> 
> Events arrive once, thread-safely (OnNext call). End of sequences is 
> notified once with success or failure, so cleanup is trivial.

Well, how is that triviality any new or groundbreaking? The interfaces I 
have in Simple Components for communication protocols are just like this.

> The emitter of events is an Observable. The consumer is an Observer. 
> Combinations of both are Operators. There are many predefined Operators 
> to make life easy, addressing most needs that would be otherwise complex 
> (e.g. tasking ones).

Since I am using this model too, this is by no means any better than 
other methods. In fact it is far worse! The reason why I am using it is 
because there is no other way dealing with asynchronous I/O under the 
constraint of limited number of tasks. The implementations of all 
protocols in Simple Components are asynchronous.

Now, programming this is like scratching your left ear with the right 
hand. I keep on asking for co-routines in Ada to break out of this lousy 
awful mess. To rein assorted mess of events/callbacks into a sequence 
imperative calls to be a able to program it as if it were an 
uninterrupted thread of control maintaining its state, just like if the 
I/O were synchronous.

> For my own specification package: https://goo.gl/WQfpeV

Good work, BTW.

[...]

> Since you asked about TreeViews elsewhere, I see they somehow do it (but 
> don't ask me how. It's probably ugly JS):
> https://react.rocks/tag/TreeView

Too simple to judge. Usually problems start with columns, rendering 
nodes differently depending on conditions, evaluation of the three 
dimensions etc.

>> [There is nothing simple or elegant in event-controlled architectures. 
>> Doing this for 20+ years (this is state of the art in automation 
>> systems), I am pretty sure of.]
> 
> The most elegant designs can turn ugly once things get real, that's for 
> sure...

No. This is another set properties: scalability, composability.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de